In a laboratory environment, particularly in laboratories working with biologically active materials, it is important to have a secure means of supporting an array of test tubes, often in a predetermined order, and of transporting and storing them between uses. Among the desirable features in such a product are: transparency, so that the test tubes and their contents are readily visible; nestability, so that the parts of the test tube rack may be compactly nested when not in use; stackability, so that assembled test tube racks may be stacked one on top of the other for storage; and disposability, so that a rack containing a group of used test tubes may be disposed of as a unit, thereby avoiding the need to remove the tubes individually and the need to clean and sterilize the test tube rack for re-use.
To accomplish at least some of the above purposes, a number of devices are disclosed by the prior art, including the following.
Delair U.S. Pat. No. 3,184,071 (May 18, 1965) discloses an injection-molded plastic case for various kinds of containers, including glass containers, in which the principal embodiment has both a central perforated rack and a similarly perforated cover to give two levels of support to hold the containers in an upright position.
Mander, et al. U.S. Pat. No. 3,643,812 (Feb. 22, 1972) shows a storage rack intended specifically for test tubes. It incorporates a base unit and a cooperating cover unit, both made of vacuum-formed thermoplastic such as polypropylene, in which the base unit is a one-piece deep-drawn bucket shape having at its bottom a plurality of evenly spaced tetrahedron-shaped wells, each adapted to receive and support an individual test tube. A drain opening is provided at the bottom of each well to permit condensate to escape.
Korum U.S. Pat. No. 4,284,603 (Aug. 18, 1981) discloses a three-piece test tube rack, open at the sides, in which the component parts may be stored separately and then snapped together for use. The top component has clear-through openings allowing the test tubes to be inserted; the middle component has corresponding clear-through openings for center support; and the base component has semi-closed wells instead of clear-through openings to prevent the test tubes from falling out while still allowing drainage. The base and cover are therefore of necessity not identical, although the specification suggests that the base and cover can be produced using the same mold (col. 3, lines 1-3). Clearly a separate supply of both tops and bases would have to be kept on hand in order to use the device at all, which is a problem solved by the present invention.
Mehra U.S. Pat. No. 4,588,095 (May 13, 1986) shows a complex one-piece injection molded test tube rack having perforated wells at the bottom, and grids for the middle and top supports. The claimed invention resides in the device as a single integral piece, distinguishing it from multi-component units which allow compact nested storage prior to assembly for use, as with the present invention.